Heretofore, COF (Chip on Film) packages such as a non-contact type ID card and a non-contact type tag have been manufactured by various methods.
As an example there is known a method in which bumps (salient electrodes) formed on an IC chip are aligned with electrodes of an antenna circuit formed on a resin film substrate, then the IC chip is pressed to effect flip chip bonding, and subsequently resin is filled into a slight gap (or a slight space) between the resin film substrate and the IC chip, that is, under-fill is performed.
As another example there is known a method in which a semi-hardened anisotropic conductive film is affixed to electrodes of an antenna circuit formed on a resin film substrate, then bumps (salient electrodes) formed on an IC chip are aligned with the electrodes of the antenna circuit, then the IC chip is pressed under heating to bond the electrodes and harden the anisotropic conductive film.
Thus, in each of these known methods, an IC chip is mounted in a stacked form onto the surface of a substrate having an antenna circuit, and thus a limit is encountered in reducing the package thickness.
In an effort to avoid such an inconvenience, for example as is disclosed in Japanese Published Examined Patent Application No. 70272/1991, there has been proposed a method (hereinafter referred to as the IC chip buried type manufacturing method) in which a resin film substrate having a chip mounting hole and an IC chip having electrodes are provided, then the IC chip is inserted and fixed into the chip mounting hole so as to expose the electrodes above the substrate surface, and thereafter a circuit pattern for connection with the electrodes is formed on the substrate surface.
In this known IC chip buried type manufacturing method, however, since the IC chip is inserted into the chip mounting hole formed in the resin film substrate, it is necessary that the chip mounting hole be formed larger than the IC chip, with consequent formation of a slight gap (or a slight space) between the inserted IC chip and the mounting hole. Therefore, a resin of the same quality as the substrate is filled into the slight gap, followed by hot pressing for fusion-bonding of the two.
In the fusion-bonding, the resin film substrate itself, which is thin, is apt to be deformed and there further arises a problem that the IC chip shifts under a pressing force and its position varies and does not become fixed. Due to this problem, at the time of forming a circuit pattern onto the substrate surface after the insertion and fixing of the IC chip into the chip mounting hole, it is troublesome to form the circuit pattern accurately with respect to the electrodes on the IC chip, that is, in such a state as is free from a larger positional deviation than a predetermined limit, and thus the constant quality cannot be maintained sufficiently.
As one means for solving this problem there has been proposed the adoption of a resin pouring method instead of the aforesaid hot pressing, but the aforesaid means involves complicated manufacturing steps and requires a long processing time. For these reasons it is not suitable for mass production of COF packages and the adoption thereof has so far been difficult.
The present invention has been accomplished in view of such drawbacks and it is a first object of the invention to provide a method of manufacturing a COF package which, when a COF package is to be obtained by the IC chip buried type manufacturing method, permits an IC chip to be buried in such a state as is free from a larger positional deviation than a predetermined limit and which thereby affords a COF package of a constant quality. It is a second object of the present invention to permit mass production of COF packages having a constant quality.